There is so much coffee out there! There is over 2.25 billion cups of coffee consumed every single day.
With that much coffee in our systems, no wonder there is a whole day dedicated to celebrating it! October 1st is International coffee day and as coffee aficionados, Healthy Homes and Gardens has decided to explore some coffee samples using the Bruker M4 TORNADO.
The majority of people who like coffee consume it as a beverage, so get your brew ready, get comfy and drink up this article all about coffee.
A bite sized introduction to coffee production
Brazil is the top producer of coffee, with Vietnam and Columbia coming in second and third, respectively. Interestingly, the areas in which coffee is supplied from is subtropical and tropical environments. The price of coffee worldwide is approximated at $2 billion per year. In other words – it makes up 1% of world trade. In fact, majority of the countries who produce coffee rely on the exportation as a main source of GDP. That is a lot of caffeine
Two samples of Daley Street Medium Coffee Ground from Coles were analysed, one was used coffee grounds, the other unused (Figure 1). According to Coles, the Daley Street Medium Coffee Ground is a mix of arabica beans from Colombia and Kenya. For this analysis the two samples were analysed side by side in the Bruker M4 TORNADO. It was scanned at 100µm, 20 ms/pixel at 45kV and 600µA.
Figure 1: Image of a subsample of unused coffee grounds (right side) and used coffee grounds (left side).
What we found:
Calcium, potassium, iron and titanium were present in the samples, with potassium and calcium as the main constituents. Calcium was seen in both samples, in similar amounts (Fig. 2a). As expected, the coffee grounds are vary in size and shape and therefore height within the instrument and so the irregularity in the composition between the two samples is confirmed using the heat map (Fig. 2b).
Figure 2a: Ca elemental map of both samples. Right Side unused coffee grounds, left side used coffee grounds.
Figure 2b: Ca heat map of both samples. Right Side unused coffee grounds, left side used coffee grounds.
Potassium has the most variation between the two samples (Fig. 3a, 3b). The unused coffee grounds showed a substantial concentration of potassium, which is not observed in the used coffee grounds.
Figure 3a: K elemental map of both samples. Right Side unused coffee grounds, left side used coffee grounds.
Figure 3b: K heat map of both samples. Right Side unused coffee grounds, left side used coffee grounds.
Iron and titanium were also identified in the used coffee grounds, however, is only in specific grains (Fig. 4, 5).
Figure 4: Fe heat map of both samples. Right Side unused coffee grounds, left side used coffee grounds.
Figure 5: Ti heat map of both samples. Right Side unused coffee grounds, left side used coffee grounds.
What this means:
The most noticeable difference in intensities between the two samples was the shift in potassium. A study from 2017 also commented on this effect when analysing various ground coffee samples, stating it was likely that water drags these elements during the brewing process. This could suggest that the brewing process which involves heat and water contribute to the potassium leaving the sample (therefore lowering the concentration).
In terms of the iron and titanium presence in the used coffee grounds, it is unlikely these came from the coffee grounds themselves, as it is not present in the unused coffee grounds from the same product. This is also because other elements of interest seemed to be homogenous in elemental presence and distribution. These grains may potential be a contaminant, as the used sample was dried outside and may have infiltrated into the coffee.
What is great about these results is that there were no heavy elements in the samples, making this coffee really great to drink. Potassium being dragged into the water also could mean that drinking this particular coffee is giving the drinker a good amount of potassium.
We hope you had a great international coffee day and stay caffeinated.
 Hernandez, Maria Cristina, Dario Romero, Humberto Torres, Javier Miranda, and A. LÓPEZ. "X-ray fluorescence analysis of ground coffee." (2017).